Hi All, Looking for your advice on when you die cut on your heidelberg windmill. We have been die cutting alot in the past without any problems, However two days in a row now whilst die cutting the top clamp has worked its way out past the top of the cutting jacket and has ended up in the press damaging two sets of die cutting formes. We also have our jacket taped to the platen down low to help keep in it place
So the question - what one earth is making this happen? Pretty annoyed to have damaged two cutting forms and hope like hell the impression when it hits the falling clamp hasn’t done damage to the press.
So whats wrong? Could my clamps be not perfectly straight casing movement? Could it be the jacket? Or something totally different?
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On my windmill the die cutting jacket just clips on, nothing holds it. The clamp you are talking about is it the round rod for holding the top sheet in place. Dick G.
If you die cut two jobs in one day then you are doing too much for anything other than a proper jacket( bar plate makes a good one the original is also screwed down. I would not farm out a job to anyone that is taping metal to the bed to save a few bucks.
Taped down plates can be dislodged and cause damage to the press or the die especially one of mine.
Hello, our press came with a few jackets which only had one top fold in which with a top typman clamp attached to the press. Was taught to tape down the lower end of the jacket to give it just that little extra (and also holding any packing in behind the jacket).
Have today discovered their are jackets with a top and bottom snap which seems a far bloody better system.
Have discovered different grades in steel for the jackets. Some are more economical (around the $100 mark) and others which are a tougher grade for around the $400 mark. Thoughts on if the more expensive ones are worth it for smaller die cutting jobs on 300gsm cotton stock?
If you use bar plate the boxmaker jacket is more expensive but I diecut everyday on my H platen and have used the same boxmaker jacket for 16 years.
Note the theory is that the die knife penetrates 90-95% of the way into the stock to make the cut and should not hit the jacket.
I die cut a lot on my heidleburg, i’m not as old as Mike, but my jacket is around 15 years old, they do last a long time if you don’t hit them too hard. Dick G.
We die-cut on three small Heidelbergs and one large one, using Bar-Plate .030” (stainless?) steel jackets. These have two projections at the bottom which clip under the platen, and a crimped lip at the top that also snaps over the platen. In my experience, the press platens are not entirely identical in the short dimension—a jacket that is snug on one press slips easily on another. The jackets, and/or the packing tends to work towards the tail (flywheel side) during the run, so I will usually insert the top tympan bail to try to hold the jacket in place, which is necessary for scores that run the short dimension. The tympan bale is not intended for this purpose, as Dick notes above, and it doesn’t fit every jacket and every press. I suspect you simply haven’t got sufficient room at the top of the jacket for the bail to hold securely; seems dangerous to me.
A loose-fitting jacket can be tightened up by peening over the lip at the top or the ears underneath; I don’t know if a too-tight jacket can be opened up similarly.
We do a lot of die-cutting, and replace the jackets every couple of years or so. We tend to pack them to .038 or .040” for most work (.034” or so for kiss-cutting , also called face-slitting). We score on the jackets, getting position with a perf rule first. Our cutting and perfing rules are .918”; .890, .895, or .900 scoring rule, depending on stock thickness.
The last couple of 10 x 15” Bar-Plate jackets we have ordered have been constructed differently from our older ones, and I don’t like the new ones as well. They seem to have sharp corners, and the lip has been bent in a way that precludes using a bail. Nor has fit been good.
Make sure that your guides will slide under the rear ear at the bottom of the plate, and are not prevented from rising completely by the ear. I have ground off the back lip on the rear brass guide so that it slides freely and rises completely. I use nickel guides on several of the presses, but on one, the jacket blocks the guide from rising. I tape little tabs of paper to the jacket near the guides to hold the paper out and prevent it from sliding beneath the nickel guide.
Now you know what I know. Hope this helps.
Be sure the jacket is put on with the long tab at the top of the platen and the shorter ones at the bottom. I had a friend who got it upside down and it worked loose and the gripper caught the corner of the plate and bent it. We had to replace it. Ron
Thanks all for the good advice - our new jacket was express posted from one end of the country to the other last night and straight on our press this morning. My goodness, wish I had know that snap on jackets were available years ago. Been dealing with our cranky clamped varieties for way too long.
New jacket fits super snug, snaps on beautifully - and thankfully Ron, we didn’t make the same mistake as your friend.
Off to happily cut away. Thanks all again!
Just a little note…if you’re using guides with the plate. The guides can hit the tabs on the bottom and affect how you have them adjusted. It’s probably best to slide them to where they don’t hit the tabs. Ron
Thanks Ron - good idea! Hadn’t given much thought to the guides hitting the jacket!